[PATCH 3/9] scripts/performance: Refactor dissect.py

[Ahmed Karaman <ahmedkhaledkaraman@gmail.com>]

- Apply pylint and flake8 formatting rules to the script.
- Move syntax and usage exmaple to main() docstring.
- Update get_jit_line() to only detect the main jit call.
- Use mypy for specifying parameters and return types in functions.

Signed-off-by: Ahmed Karaman <ahmedkhaledkaraman@gmail.com>
---
 scripts/performance/dissect.py | 123 ++++++++++++++++++---------------
 1 file changed, 68 insertions(+), 55 deletions(-)

diff --git a/scripts/performance/dissect.py b/scripts/performance/dissect.py
index bf24f50922..d4df884b75 100755
--- a/scripts/performance/dissect.py
+++ b/scripts/performance/dissect.py
@@ -1,34 +1,27 @@
 #!/usr/bin/env python3
 
-#  Print the percentage of instructions spent in each phase of QEMU
-#  execution.
-#
-#  Syntax:
-#  dissect.py [-h] -- <qemu executable> [<qemu executable options>] \
-#                   <target executable> [<target executable options>]
-#
-#  [-h] - Print the script arguments help message.
-#
-#  Example of usage:
-#  dissect.py -- qemu-arm coulomb_double-arm
-#
-#  This file is a part of the project "TCG Continuous Benchmarking".
-#
-#  Copyright (C) 2020  Ahmed Karaman <ahmedkhaledkaraman@gmail.com>
-#  Copyright (C) 2020  Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
-#
-#  This program is free software: you can redistribute it and/or modify
-#  it under the terms of the GNU General Public License as published by
-#  the Free Software Foundation, either version 2 of the License, or
-#  (at your option) any later version.
-#
-#  This program is distributed in the hope that it will be useful,
-#  but WITHOUT ANY WARRANTY; without even the implied warranty of
-#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-#  GNU General Public License for more details.
-#
-#  You should have received a copy of the GNU General Public License
-#  along with this program. If not, see <https://www.gnu.org/licenses/>.
+"""
+Print the percentage of instructions spent in each phase of QEMU
+execution.
+
+This file is a part of the project "TCG Continuous Benchmarking".
+
+Copyright (C) 2020  Ahmed Karaman <ahmedkhaledkaraman@gmail.com>
+Copyright (C) 2020  Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <https://www.gnu.org/licenses/>.
+"""
 
 import argparse
 import os
@@ -36,23 +29,26 @@ import subprocess
 import sys
 import tempfile
 
+from typing import List
+
 
-def get_JIT_line(callgrind_data):
+def get_jit_line(callgrind_data: List[str]) -> int:
     """
     Search for the first instance of the JIT call in
     the callgrind_annotate output when ran using --tree=caller
     This is equivalent to the self number of instructions of JIT.
 
     Parameters:
-    callgrind_data (list): callgrind_annotate output
+    callgrind_data (List[str]): callgrind_annotate output
 
     Returns:
     (int): Line number
     """
     line = -1
-    for i in range(len(callgrind_data)):
-        if callgrind_data[i].strip('\n') and \
-                callgrind_data[i].split()[-1] == "[???]":
+    for (i, callgrind_datum) in enumerate(callgrind_data):
+        if callgrind_datum.strip('\n') and \
+                callgrind_datum.split()[-1] == "[???]" and \
+                callgrind_datum.split()[1] == "*":
             line = i
             break
     if line == -1:
@@ -61,6 +57,18 @@ def get_JIT_line(callgrind_data):
 
 
 def main():
+    """
+    Parse the command line arguments then start the execution.
+    Syntax:
+    dissect.py [-h] -- <qemu executable> [<qemu executable options>] \
+                 <target executable> [<target executable options>]
+
+    [-h] - Print the script arguments help message.
+
+    Example of usage:
+    dissect.py -- qemu-arm coulomb_double-arm
+    """
+
     # Parse the command line arguments
     parser = argparse.ArgumentParser(
         usage='dissect.py [-h] -- '
@@ -76,7 +84,7 @@ def main():
 
     # Insure that valgrind is installed
     check_valgrind = subprocess.run(
-        ["which", "valgrind"], stdout=subprocess.DEVNULL)
+        ["which", "valgrind"], stdout=subprocess.DEVNULL, check=False)
     if check_valgrind.returncode:
         sys.exit("Please install valgrind before running the script.")
 
@@ -93,7 +101,8 @@ def main():
                                      "--callgrind-out-file=" + data_path]
                                     + command),
                                    stdout=subprocess.DEVNULL,
-                                   stderr=subprocess.PIPE)
+                                   stderr=subprocess.PIPE,
+                                   check=False)
         if callgrind.returncode:
             sys.exit(callgrind.stderr.decode("utf-8"))
 
@@ -102,7 +111,8 @@ def main():
             callgrind_annotate = subprocess.run(
                 ["callgrind_annotate", data_path, "--tree=caller"],
                 stdout=output,
-                stderr=subprocess.PIPE)
+                stderr=subprocess.PIPE,
+                check=False)
             if callgrind_annotate.returncode:
                 sys.exit(callgrind_annotate.stderr.decode("utf-8"))
 
@@ -120,25 +130,28 @@ def main():
         total_instructions = int(total_instructions.replace(',', ''))
 
         # Line number with the JIT self number of instructions
-        JIT_self_instructions_line_number = get_JIT_line(callgrind_data)
+        jit_self_instructions_line_number = get_jit_line(callgrind_data)
         # Get the JIT self number of instructions
-        JIT_self_instructions_line_data = \
-            callgrind_data[JIT_self_instructions_line_number]
-        JIT_self_instructions = JIT_self_instructions_line_data.split()[0]
-        JIT_self_instructions = int(JIT_self_instructions.replace(',', ''))
+        jit_self_instructions_line_data = \
+            callgrind_data[jit_self_instructions_line_number]
+        jit_self_instructions = jit_self_instructions_line_data.split()[0]
+        jit_self_instructions = int(jit_self_instructions.replace(',', ''))
 
         # Line number with the JIT self + inclusive number of instructions
-        # It's the line above the first JIT call when running with --tree=caller
-        JIT_total_instructions_line_number = JIT_self_instructions_line_number-1
+        # It's the line above the first JIT call when running with
+        # --tree=caller
+        jit_total_instructions_line_number = \
+            jit_self_instructions_line_number-1
         # Get the JIT self + inclusive number of instructions
-        JIT_total_instructions_line_data = \
-            callgrind_data[JIT_total_instructions_line_number]
-        JIT_total_instructions = JIT_total_instructions_line_data.split()[0]
-        JIT_total_instructions = int(JIT_total_instructions.replace(',', ''))
+        jit_total_instructions_line_data = \
+            callgrind_data[jit_total_instructions_line_number]
+        jit_total_instructions = jit_total_instructions_line_data.split()[0]
+        jit_total_instructions = int(jit_total_instructions.replace(',', ''))
 
         # Calculate number of instructions in helpers and code generation
-        helpers_instructions = JIT_total_instructions-JIT_self_instructions
-        code_generation_instructions = total_instructions-JIT_total_instructions
+        helpers_instructions = jit_total_instructions-jit_self_instructions
+        code_generation_instructions = \
+            total_instructions-jit_total_instructions
 
         # Print results (Insert commas in large numbers)
         # Print total number of instructions
@@ -149,12 +162,12 @@ def main():
         print('{:<20}{:>20}\t{:>6.3f}%'.
               format("Code Generation:",
                      format(code_generation_instructions, ","),
-                     (code_generation_instructions / total_instructions) * 100))
-        # Print JIT instructions and percentage
+                     (code_generation_instructions/total_instructions)*100))
+        # Print jit instructions and percentage
         print('{:<20}{:>20}\t{:>6.3f}%'.
-              format("JIT Execution:",
-                     format(JIT_self_instructions, ","),
-                     (JIT_self_instructions / total_instructions) * 100))
+              format("jit Execution:",
+                     format(jit_self_instructions, ","),
+                     (jit_self_instructions / total_instructions) * 100))
         # Print helpers instructions and percentage
         print('{:<20}{:>20}\t{:>6.3f}%'.
               format("Helpers:",
-- 
2.17.1